Afghani Army and Police forces have suffered IMMENSE casualties in the past few years. In 2015 their police lost almost 3700 personnel.
Numbers for 2016 and 2017 are now considered a state secret, since the release of this figure caused concern in the population when it was released in 2015. For a police force that has only 150.000 employees (including civilians, even gardeners or janitors for larger bureaucratic facilities etc.) those are massive losses. Assuming that for every man "under arms" there are 5 in civilian clothes that would make only 25 000 armed personnel.
3700 losses per annum is an extremely high number, more than 10% of armed personnel. Of course they would run into trouble arming the replacements.